image/png: panic in reader.go

[Deleplace]

Please answer these questions before submitting your issue. Thanks!

What version of Go are you using (go version)?

go version go1.8 linux/amd64

What operating system and processor architecture are you using (go env)?

GOARCH="amd64"
GOBIN=""
GOEXE=""
GOHOSTARCH="amd64"
GOHOSTOS="linux"
GOOS="linux"
GOPATH="/home/valentin/Documents/2017/03/21/goDLL"
GORACE=""
GOROOT="/usr/local/go"
GOTOOLDIR="/usr/local/go/pkg/tool/linux_amd64"
GCCGO="gccgo"
CC="gcc"
GOGCCFLAGS="-fPIC -m64 -pthread -fmessage-length=0 -fdebug-prefix-map=/tmp/go-build002149362=/tmp/go-build -gno-record-gcc-switches"
CXX="g++"
CGO_ENABLED="1"
PKG_CONFIG="pkg-config"
CGO_CFLAGS="-g -O2"
CGO_CPPFLAGS=""
CGO_CXXFLAGS="-g -O2"
CGO_FFLAGS="-g -O2"
CGO_LDFLAGS="-g -O2"

What did you do?

image.Decode(r2) where r2 is reading a PNG image that looks ok to me.
See attached source.
(texture1, r1 are there just to demonstrate the happy path).
See self-contained code at https://play.golang.org/p/gkXmcSjbwq

What did you expect to see?

At best, no error at all.
Otherwise, image.Decode should return an error with some nice message.

What did you see instead?

2017/03/28 13:58:41 Texture 1
2017/03/28 13:58:41 size = 737
2017/03/28 13:58:41 format = jpeg
2017/03/28 13:58:41 err = <nil>
2017/03/28 13:58:41 
2017/03/28 13:58:41 Texture 2
2017/03/28 13:58:41 size = 1031
panic: runtime error: invalid memory address or nil pointer dereference
[signal SIGSEGV: segmentation violation code=0x1 addr=0x0 pc=0x4a9d68]

goroutine 1 [running]:
image/png.(*decoder).readImagePass(0xc42002d800, 0x7f75cf6f4088, 0xc420018230, 0x0, 0xc420018200, 0x0, 0x0, 0xc420092000, 0xc42002d878)
	/usr/local/go/src/image/png/reader.go:615 +0x1028
image/png.(*decoder).decode(0xc42002d800, 0x0, 0x0, 0x0, 0x0)
	/usr/local/go/src/image/png/reader.go:365 +0x621
image/png.(*decoder).parseIDAT(0xc42002d800, 0x3c0, 0x4e6d5e, 0x4)
	/usr/local/go/src/image/png/reader.go:827 +0x36
image/png.(*decoder).parseChunk(0xc42002d800, 0x0, 0x0)
	/usr/local/go/src/image/png/reader.go:887 +0x45a
image/png.Decode(0x7f75cf6f4030, 0xc420014240, 0xc420014240, 0x7f75cf6f4030, 0xc420014240, 0x8)
	/usr/local/go/src/image/png/reader.go:946 +0x161
image.Decode(0x54f140, 0xc420016510, 0x407, 0xc420070900, 0x407, 0x480, 0x0, 0x0)
	/usr/local/go/src/image/format.go:84 +0xfc
main.main()
	/home/valentin/Documents/2017/03/28/tecrash/read.go:27 +0x677
exit status 2

[Deleplace]

issue_19738_panics.zip

[Deleplace]

Texture 2 may or may not contain some corrupt bytes.

It looks ok on my desktop and on GitHub.
And the real problem is in the png decoder panicking (I would be ok with just an error properly returned).

[dgryski]

Does this fail on tip? It may be a duplicate of #19553

[odeke-em]

@dgryski, good hunch. It doesn't panic anymore on tip 73912a1

$ go version && go run main.go && echo success
go version devel +73912a1 Mon Mar 27 18:41:30 2017 -0600 darwin/amd64
2017/03/28 09:30:29 Texture 1
2017/03/28 09:30:29 size = 737
2017/03/28 09:30:29 format = jpeg
2017/03/28 09:30:29 err = <nil>
2017/03/28 09:30:29 
2017/03/28 09:30:29 Texture 2
2017/03/28 09:30:29 size = 1031
2017/03/28 09:30:29 format = png
2017/03/28 09:30:29 err = <nil>
success

@Deleplace please get the latest from the master branch.

[odeke-em]

Can't reproduce on the latest. Please reopen if it persists.

[Deleplace]

Thanks! I had performed a quick search for "png decode" in issues, but for some reason I had not seen #19553. It looks the same, I will try on tip.

[Deleplace]

Not reproduced on recent 4b50c81 . Great!